Traveling dark-bright solitons in a reduced spin-orbit coupled system: application to Bose-Einstein condensates

TL;DR

This paper investigates the existence and dynamics of dark-bright solitons in spin-orbit coupled Bose-Einstein condensates, using multiscale analysis and exploring their behavior in trapping potentials.

Contribution

It introduces a multiscale reduction to the Mel'nikov system for analyzing dark-bright solitons in spin-orbit coupled BECs, providing new insights into their propagation and oscillation properties.

Findings

Traveling dark-bright solitons can be approximated using the Mel'nikov system.

Solitons propagate undistorted for small perturbations and shed radiation for larger ones.

Oscillation frequency depends on bright component mass and Raman wavenumber.

Abstract

In the present work, we explore the potential of spin-orbit (SO) coupled Bose-Einstein condensates to support multi-component solitonic states in the form of dark-bright (DB) solitons. In the case where Raman linear coupling between components is absent, we use a multiscale expansion method to reduce the model to the integrable Mel'nikov system. The soliton solutions of the latter allow us to reconstruct approximate traveling DB solitons for the reduced SO coupled system. For small values of the formal perturbation parameter, the resulting waveforms propagate undistorted, while for large values thereof, they shed some dispersive radiation, and subsequently distill into a robust propagating structure. After quantifying the relevant radiation effect, we also study the dynamics of DB solitons in a parabolic trap, exploring how their oscillation frequency varies as a function of the bright component mass and the Raman laser wavenumber.